The present invention relates to a safety seat belt system for use in a vehicle, especially in an automotive vehicle, which system may effectively and safely absorb the impact energy during a collision or the like.
There has been devised and demonstrated an impact energy absorbing device for use with a seat belt system wherein the impact energy acting upon a seat belt due to the sudden acceleration of an occupant during a collision or the like is converted into the force for bending a U-shaped steel strip. However, the greater frictional resistance is generated between the U-shaped strip and a case to which is firmly attached one end of the strip when the strip is bent so that the critical load can not be fixed. As a result, the desired impact energy absorbing characteristics cannot be attained. Furthermore since the U-shaped steel strip and the case are formed integral, in determining a set load limit not only the force for bending the U-shaped strip but also the force for shearing the U-shaped strip away from the case must be taken into consideration. Thus, the conventional energy absorbing device is not satisfactory in practice. Moreover, its energy absorbing efficiency is unsatisfactory. To improve the efficiency, the steel strip must have a greater thickness and width, thus resulting in the increase in the size of the shock absorbing device. Therefore, it becomes impossible to install the energy absorbing device in the space above the shoulder of an occupant.